A two-terminal synapse device based on multi-carbonyl semiconductor sodium ion storage and a preparation method thereof

Abstract

The application relates to a two-terminal synapse device based on multi-carbonyl semiconductor sodium ion storage and a preparation method thereof, and belongs to the technical field of organic semiconductor electronic devices. The two-terminal synapse device is prepared by adopting a multi-carbonyl semiconductor as a semiconductor functional layer and a solid-state electrolyte containing sodium ions as an ion supply layer. The application utilizes the characteristics and excellent kinetics of the multi-carbonyl semiconductor in high-density storage / release of sodium ions, realizes continuous modulation of the conductance state of the device, deeply imitates the synaptic plasticity of biological nerves according to the electrochemical principle, and simulates a fully-connected neural network. The solid-state thin film device is highly imitated and is expected to be large-scale integrated, and is applied to a future neuromorphic chip.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic semiconductor electronic devices, in particular to a two-terminal synapse device based on multi-carbonyl semiconductor sodium ion storage and a preparation method thereof. BACKGROUND

[0002] Developing synapse devices that simulate biological information processing processes is crucial for the hardware implementation of brain-like computing systems. Two-terminal synapse devices can record voltage and current changes according to their resistance states, and their continuously modulated resistance and memory states are very similar to biological synapse responses. In addition, the devices are easy to integrate into crossbar arrays, so they are expected to realize large-scale integrated brain-like computing systems.

[0003] Synapses are the sites where biological neurons functionally connect and the key sites for information transmission. During information transmission, the inward flow of sodium ions generates a local depolarization potential on the postsynaptic membrane, which in turn triggers the initiation of an action potential in the neuron axon, completing the information transmission. Therefore, sodium ion-driven bionic synapse devices are expected to deeply simulate various functions in biological nerves dominated by sodium ion activity, and promote the construction of synapses based on neural synapses and the development of neuromorphic chips.

[0004] Due to the unclear electrochemical mechanism of sodium ion storage in semiconductor thin films and the difficulty in simulating ion migration in biological nerves, there are few reports on sodium ion-based biomimetic synaptic devices. Recently, it has been found that metal chalcogenides and oxides such as selenium sulfide (SnS2), zinc oxide (ZnO) and titanium dioxide (TiO2) can be used to realize biomimetic synaptic devices, realize the doping and dedoping of sodium ions under an electric field, and exhibit excellent synaptic plasticity and memristive function (Nanoscale, 2019, 11, 15382-15388; J. Mater. Chem. C, 2021, 9, 5396-5402; Materials Today Physics, 2021, 18, 100329.). Organic semiconductors have adjustable energy bands, rich functional group sites and excellent electrochemical redox activity, and are expected to highly mimic the kinetic behavior of various anions and cations in the synapse, and thus design excellent ion-type biomimetic synaptic devices. Especially, polycarbonyl compounds as a kind of excellent n-type semiconductor can store and release a variety of metal cations including sodium ions at high density, and the related ion kinetic mechanism has been widely used in the design and development of organic battery materials (Adv. Sci. 2019, 6, 1900431.). Although Dongshin Kim et al. first used disodium terephthalate to mimic the liquid-state synaptic device for sodium ion storage (NPG Asia Materials, 2020, 12, 1-7.), the use of liquid electrolyte limits its further development, and a sodium ion storage-based polycarbonyl semiconductor memristor in a solid-state thin film has not been reported. Therefore, by using the sodium ion storage characteristics and excellent kinetics of polycarbonyl semiconductors under electrochemical conditions, a two-terminal biomimetic synaptic device is designed and constructed, which is expected to deeply simulate the synaptic plasticity dominated by sodium ion activity in biological nerves, and has the potential to realize large-scale integration and future neuromorphic chips. SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] For cation-driven neuromorphic devices, in view of a series of problems of sodium ion biomimetic synaptic plasticity, the present application realizes continuous modulation of the conductive state of the device by using the electrochemical insertion and extraction of sodium ions in a solid-state thin film under voltage driving, deeply biomimics the synaptic plasticity of biological nerves by electrochemical principle and simulates the fully connected neural network. The selectivity of sodium ion channels and ion kinetics in the solid-state thin film synaptic device are difficult to be imitated, and a series of synaptic plasticity problems are solved. The solid-state thin film device highly imitates and is expected to be large-scale integrated, and applied to future neuromorphic chips.

[0007] TECHNICAL SCHEME

[0008] The application realizes electrochemical insertion and extraction of sodium ions to the semiconductor functional layer under voltage driving to adjust the conductance state of the synaptic device.

[0009] A two-terminal synaptic device based on polycarbonyl semiconductor sodium ion storage, characterized by comprising a semiconductor functional layer, an ion supply layer, a bottom electrode and a top electrode; the material used in the semiconductor functional layer is a polycarbonyl compound; the material used in the ion supply layer is a sodium ion-containing polymer or a sodium ion polymer.

[0010] A further technical solution of the application: the polycarbonyl compound includes but is not limited to 5,7,12,14-pentacene tetrone (Pentacenetetrone), perylene tetracarboxylic dianhydride (PTCDA), 3,4,9,10-tetracarboxyldiimide (PTCDI), poly(phenanthroline-9,10-diketone-2,7-diyl) (Poly-PA), poly(anthraquinone-9,10-diyl) (Poly-AQ), poly(anthraquinone-1,5-diyl) (Poly-1,5AQ), poly[(cyclohexa-2,5-diene-1,4-dione-2,5-diyl)-alternating-sulfur] (Poly-BQ-S), poly[(anthraquinone-1,4-diyl)-alternating-sulfur] (Poly-AQ-S), poly[(anthraquinone-1,5-diyl)-alternating-sulfur] (Poly-1,5AQ-S), poly naphthalene dithiophene (PNDI(2OD)2T), poly naphthalene diimide-thiophene (PNDI(2HD)T) and poly[[1,2,3,6,7,8-hexahydro-2,7-bis(2-octyldodecyl)-1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-4,9-diyl] (3,3'-difluoro[2,2'-bithiophene]-5,5'-diyl)] (PNF222), poly[(benzimidazolyl)benzophenanthroline] (BBL).

[0011] A further technical solution of the application: the sodium ion-containing polymer is an electrolyte salt, a solvent and a gel polymer, wherein the electrolyte salt includes but is not limited to sodium chloride (NaCl), sodium perchlorate (NaClO4), sodium sulfate (Na2SO4), sodium octyl sulfate (C8H 17 NaO4S), sodium poly-L-glutamate, sodium 1-naphthalenesulfonate (C 10 H7NaO3S), sodium malonate (CH2(COONa)2), sodium tetradecanoate (CH3(CH2) 12 COONa), sodium 1,5-naphthalene disulfonate (C 10H6Na2O6S2, etc.; solvents include but are not limited to ethyl carbonate, water, acetonitrile, ethylene carbonate (EC), diethyl carbonate (DEC), acetone, etc.; gel polymers include but are not limited to polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer P(VDF-TrFE), poly(styrene-block-methyl methacrylate-block-styrene) (PS-PMMA-PS), polyvinylidene fluoride-hexafluoropropylene copolymer (P(VDF-HFP)), gelatin, chitosan, etc.; the mass ratio of electrolyte salt, solvent and gel polymer is 1:2:3-5:6:9.

[0012] Further technical solutions of the present application: the sodium ion polymer includes but is not limited to sodium polyacrylate, poly(styrene sodium sulfonate) (PSSNa), poly(sodium methacrylate) (PMA).

[0013] Further technical solutions of the present application: the materials used for the bottom electrode and the top electrode include but are not limited to indium tin oxide (ITO), gold, platinum, titanium, silver, copper, aluminum; the bottom electrode and the top electrode are prepared by vacuum evaporation or magnetron sputtering, and the thickness is 5-500 nm.

[0014] Further technical solutions of the present application: the semiconductor functional layer is prepared by thermal evaporation or spin coating or spraying process, and the thickness is 1-500 nm.

[0015] Further technical solutions of the present application: the ion supply layer is prepared by spin coating or blade coating process, and the thickness is 1-100 microns.

[0016] A preparation method of a two-terminal synapse device based on multi-carbonyl semiconductor sodium ion storage, characterized by the following steps:

[0017] Step 1: clean the substrate, ultrasonically treat with acetone, isopropanol and deionized water in turn, and use nitrogen to blow and dry;

[0018] Step 2: prepare the bottom electrode on the clean substrate obtained in step 1 by magnetron sputtering or vacuum evaporation instrument;

[0019] Step 3: prepare the semiconductor functional layer on the substrate with the bottom electrode obtained in step 2 using a spin coater or a spray gun or a vacuum evaporation instrument and anneal to obtain the semiconductor functional layer;

[0020] Step 4: prepare the ion supply layer on the basis of the organic semiconductor functional layer obtained in step 3 using a spin coater or a blade coating method and anneal to obtain the ion supply layer;

[0021] Step 5: prepare the top electrode on the basis of the ion supply layer obtained in step 4 using a vacuum evaporation instrument or a magnetron sputtering, thereby obtaining a two-terminal synapse device with a complete structure.

[0022] Advantages

[0023] The application provides a two-terminal synapse device based on sodium ion storage of a multicarbonyl semiconductor and a preparation method thereof. The two-terminal synapse device is prepared by using a multicarbonyl semiconductor as a semiconductor functional layer and a solid-state electrolyte containing sodium ions as an ion supply layer. The sodium ion storage / release characteristics and excellent kinetics of the multicarbonyl semiconductor are used to realize continuous modulation of the conductive state of the device, to deeply imitate the synaptic plasticity of biological nerves by using the electrochemical principle and to simulate a fully connected neural network. The solid-state thin film device is highly imitated and is expected to be large-scale integrated and applied to a future neuromorphic chip. Compared with the prior art, the application has the following advantages:

[0024] 1. Based on the sodium ion storage / release characteristics and excellent kinetics of the multicarbonyl semiconductor, sodium ions in the solid-state thin film are electrochemically inserted and extracted into the multicarbonyl semiconductor under voltage driving, so that continuous modulation of the conductive state of the device is realized.

[0025] 2. Based on the electrochemical principle, the selectivity and ion kinetics of the sodium ion channel in the biological nerve are highly imitated, and various synaptic plasticities are successfully simulated.

[0026] 3. Based on the electrochemical process of sodium ion insertion and extraction into the multicarbonyl semiconductor, a linear and symmetric enhancement inhibition curve can be obtained by voltage pulse modulation, so that a fully connected neural network can be simulated to realize high-precision pattern recognition. The potential of the thin film device for large-scale integration and application to a neuromorphic chip is shown. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0028] Figure 1 FIG. 1 is a structural schematic diagram of a two-terminal synapse device based on sodium ion storage of a multicarbonyl semiconductor according to the application.

[0029] Figure 2 FIG. 2 is a flowchart of a two-terminal synapse device based on sodium ion storage of a multicarbonyl semiconductor prepared in an embodiment of the application.

[0030] Figure 3 FIG. 3 is a structural schematic diagram of a two-terminal synapse device based on sodium ion storage of a multicarbonyl semiconductor prepared in an embodiment of the application.

[0031] Figure 4 FIG. 4 is a cyclic I-V characteristic curve of a two-terminal synapse device based on sodium ion storage of a multicarbonyl semiconductor prepared in an embodiment of the application.

[0032] Figure 5is the analog synaptic function-excitatory post synaptic current (EPSC) curve of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application.

[0033] Figure 6 is the analog synaptic function-frequency dependent plasticity (SRDP) curve of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application.

[0034] Figure 7 is the analog synaptic function-timing dependent plasticity (STDP) curve of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application.

[0035] Figure 8 is the analog synaptic function-Bienenstock Cooper Munro learning rule (BCM) curve of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application.

[0036] Figure 9 is the analog synaptic function-potentiation and depression curve of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application.

[0037] Figure 10 is the image recognition simulation result of the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage prepared by the embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0039] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "vertical", "horizontal" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0040] Furthermore, numerous specific details are set forth in the following description of the application, such as structural details, materials, dimensions, processing steps and techniques, in order to provide a thorough understanding of the application. As will be appreciated by one skilled in the art, however, the application can be practiced without specific details. In other instances, well-known structures and functions have not been described in detail in order to avoid obscuring the application. The following detailed description is presented in connection with the accompanying drawings and certain embodiments of the application.

[0041] The application provides a two-terminal synapse device based on sodium ion storage of polycarbonyl semiconductor, which realizes continuous modulation of device conductance state and successfully simulates multiple synapse functions by using sodium ion electrochemical insertion and extraction process under voltage driving.

[0042] A two-terminal synapse device based on sodium ion storage of polycarbonyl semiconductor includes a semiconductor functional layer, an ion supply layer, a bottom electrode and a top electrode. The material used in the semiconductor functional layer is a polycarbonyl compound; the material used in the ion supply layer is a sodium ion-containing polymer (composed of electrolyte salt, solvent and gel polymer) or a sodium ion polymer.

[0043] Example 1

[0044] As shown in Figure 2 A method for preparing a two-terminal synapse device based on sodium ion storage of polycarbonyl semiconductor includes the following steps:

[0045] In step S1, a 1.5x1.5cm ITO glass substrate (100) is prepared, which has a patterned ITO as a bottom electrode (101). The substrate is ultrasonically treated with acetone, isopropanol and deionized water for 15 minutes, and then dried.

[0046] In step S2, a PTCDA semiconductor functional layer (102) is prepared on the ITO glass substrate (101) using a vacuum evaporation instrument: the substrate is placed on the sample holder of the evaporation system and fixed, and the sample holder is placed in the evaporation cavity. After placing 100-200mg of PTCDA in the evaporation crucible, the cavity is closed. At this time, the cooling system and the compression pump are started, and the power supply and vacuum gauge switches of the evaporation system are turned on. After the mechanical pump and electromagnetic valve are turned on, the molecular pump is started when the vacuum gauge reading is lower than 10Pa, and the cavity vacuum reaches 2x10 -5When the pressure is below 10 Pa, turn on the thermal evaporation power supply and set the heating current to about 30 A. Wait for the heating source to warm up and observe the frequency change of the quartz crystal oscillator on the film thickness meter. When the frequency decrease rate stabilizes, open the sample holder shutter and record the initial frequency of the film thickness meter. When the frequency decreases by 800 Hz, turn off the shutter and the heating current of the thermal evaporation power supply. Press the "stop" button of the molecular pump. When the heating current of the thermal evaporation power supply and the operating frequency of the molecular pump drop to 0, turn them off. Then turn off the electromagnetic valve, mechanical pump, power supply, start the cooling system and compression pump in sequence. Open the inlet valve of the evaporation chamber and fill it with argon until the pressure inside the vacuum chamber returns to normal. Then open the chamber to complete the preparation of the PTCDA semiconductor functional layer (102).

[0047] In step S3, an ion supply layer (103) is formed on the PTCDA semiconductor functional layer (102) using a spin coater. First, an electrolyte solution is prepared: 30 mg of PSSNa is dissolved in 1 ml of deionized water and heated on a hot plate at 55°C for 10 min to ensure complete dissolution. Then, a 0.22 μm polyvinylidene fluoride (PVDF) needle filter is used to filter the solution, followed by the addition of 12 μL of non-ionic fluorocarbon surfactant and ultrasonic dispersion for 10 min. Then, spin coating is performed at a parameter of 3000 rpm (30 s). After spin coating, the sample is annealed on a 100°C hot plate for 30 min to form an ion supply layer (103) with a thickness of 1-2 μm.

[0048] In step S4, a top electrode (104) is formed on the ion supply layer (103) using a vacuum evaporation instrument. A custom patterned top electrode mask (channel width 50 μm) is placed on the sample holder of the evaporation system. The substrate prepared in the previous step is placed on the mask and fixed. The sample holder is placed in the evaporation chamber. A 3 cm gold wire is placed in the evaporation crucible, and the chamber is closed. The cooling system and compression pump are started, and the power supply and vacuum gauge switches of the evaporation system are turned on. The mechanical pump and electromagnetic valve are turned on in sequence. When the vacuum gauge reading is below 10 Pa, the molecular pump is turned on, and the chamber vacuum reaches 2 x 10 -5When the temperature is below Pa, turn on the thermal evaporation power supply and set the heating current to about 130 A. Wait for the heating source to warm up, and observe the frequency change of the quartz crystal oscillator on the film thickness meter during heating. When the frequency of the crystal oscillator stabilizes, open the sample holder shutter. Record the frequency of the film thickness meter as the initial value. When the frequency decreases by 5000 Hz, turn off the shutter and the current switch of the thermal evaporation power supply. Press the "stop" button of the molecular pump. When the heating current of the thermal evaporation power supply and the working frequency of the molecular pump are reduced to 0, turn them off. Then turn off the electromagnetic valve, mechanical pump, power switch, start the cooling system and compression pump. Next, open the inlet valve of the evaporation instrument cavity, fill in argon until the internal pressure of the vacuum cavity returns to normal pressure, then open the cavity. Finally, the top electrode (104) is prepared, and the complete two-terminal synaptic device is completed.

[0049] The two-terminal synaptic device obtained in step S4 is tested for its memristive performance and synaptic plasticity using a Keithley 4200A-SCS semiconductor parameter analyzer and a TTPX low-temperature probe station.

[0050] When the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage is tested for its basic electrical performance, the device exhibits excellent hysteresis characteristics and continuously adjustable conductance state memristive characteristics. When the two-terminal synaptic device based on multi-carbonyl semiconductor sodium ion storage is tested for its synaptic function, the device can obtain various synaptic plasticities, including but not limited to excitatory postsynaptic current (EPSC), paired pulse facilitation (PPF), potentiation / depression of synaptic weight, spike rate-dependent plasticity (SRDP), time-dependent plasticity (STDP), Bienenstock Cooper Munro learning rule (BCM), etc.

[0051] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the scope of the present application, and these modifications or replacements should be covered within the protection scope of the present application.

Claims

1. A two-terminal synaptronic device based on polycarbonyl semiconductor sodium-ion storage, characterized by: The device comprises a semiconductor functional layer, an ion supply layer, a bottom electrode and a top electrode; the material of the semiconductor functional layer is a polycarbonyl compound; the material of the ion supply layer is a sodium ion polymer; The polycarbonyl compound is perylene tetracarboxylic diimide (PTCDA); The sodium ion polymer is sodium polyacrylate, poly(styrene sulfonic acid sodium) (PSSNa) or poly(methacrylic acid sodium) (PMA).

2. The two-terminal synapse device based on polycarbonyl semiconductor sodium ion storage according to claim 1, characterized in that: The material of the bottom electrode and the top electrode is indium tin oxide (ITO), gold, platinum, titanium, silver, copper or aluminum; the bottom electrode and the top electrode are prepared by vacuum evaporation or magnetron sputtering, and the thickness is 5-500 nm.

3. The two-terminal synapse device based on polycarbonyl semiconductor sodium ion storage according to claim 1, characterized in that: The semiconductor functional layer is prepared by a thermal evaporation or spin coating or spraying process, and the thickness is 1-500 nm.

4. The two-terminal synapse device based on polycarbonyl semiconductor sodium ion storage according to claim 1, characterized in that: The ion supply layer is prepared by a spin coating or doctor blade coating process, and the thickness is 1-100 μm.

5. The method of claim 1-4 for fabricating a two-terminal synapse device based on polycarbonyl semiconductor sodium ion storage, characterized in that, The steps are as follows: Step 1: clean the substrate, and sequentially use acetone, isopropanol and deionized water for ultrasonic treatment, and use nitrogen blowing and drying; Step 2: prepare the bottom electrode by magnetron sputtering or vacuum evaporation on the clean substrate obtained in step 1; Step 3: prepare the semiconductor functional layer on the substrate with the bottom electrode obtained in step 2 by using a spin coater or a vacuum evaporation instrument and annealing, to obtain the semiconductor functional layer; Step 4: prepare the ion supply layer on the basis of the organic semiconductor functional layer obtained in step 3 by using a spin coater or a doctor blade coating method and annealing, to obtain the ion supply layer; Step 5: prepare the top electrode on the basis of the ion supply layer obtained in step 4 by using a vacuum evaporation instrument or magnetron sputtering, to obtain a complete structure of the two-terminal synapse device.

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